1. Technical Field
The present invention is generally directed to an improved mechanism for sensing a maximum speed of a path in an integrated circuit and controlling operation of the integrated circuit timing based on the sensed maximum speed. More specifically, the present invention is directed to an apparatus and method for accurately tuning the speed of a computer chip using a built-in sense circuit and controller.
2. Description of Related Art
When integrated circuits, or chips, are manufactured, due to inaccuracies in the manufacturing methodology the integrated circuits need to be tested to determine their actual operational characteristics. Typically, these chips are sorted at the device level to segregate them into performance ranges, e.g., slow, medium and fast with respect to their expected operational speed.
The testing of these chips is typically performed with regard to the critical path or paths of the chip. That is, the critical path timing limits the speed of the chip. The testing may be performed, for example, using an AC Built-In Self Test (BIST). During AC BIST, the critical paths on the chip are exercised and the chips are sorted based on the maximum speed obtained during the test. Faster chips are sold at a premium relative to slower chips.
While such AC BIST based testing of integrated circuits provides a mechanism for sorting integrated circuits at manufacture time, the results of such testing may not be completely accurate when the integrated circuit is placed in a functional system. That is, because the functional system may have different characteristics from the test, different results may be obtained from the chip when it is placed in a functional system.
A consumer of chips that purchases chips of a particular performance range may desire to obtain additional performance out of the chips. In order to gain the additional performance, the power supply voltage is increased at the system level. However, simply increasing the supply voltage to obtain a higher level of performance is often prohibited for cooling reasons.
Thus, it would be beneficial to have an apparatus and method for sensing the maximum achievable speed of an integrated circuit in a functional system. Moreover, it would be beneficial to have an apparatus and method for sensing the achievable speed of an integrated circuit dynamically such that the speed of the integrated circuit may be dynamically controlled in a functional system.